1. Wash the inside and outside of the thermos cup with clear water first, and then carefully brush and grind every part of the cup with a little edible salt with a toothbrush. You can find that the tea stains and other attachments in the cup disappear immediately after cleaning every day, and then clean the inside and outside of the thermos cup with clear water.

2. Lemon slices are easy to wipe off the tea stains in the thermos cup, and then rinse with water.

3. Picking salt with skin can also be used to scrub tea stains with good effect.

4. Dilute it with water, pour it into a thermos cup, shake it a few times, soak it for one night, and rinse it with water the next day, and the tea stains will magically disappear.

5. Wet the cup with water first, then squeeze some toothpaste into the thermos cup, soak it for a while, then rotate it with a clean rag to wipe off the tea stains.

6. Crush the eggshell, put it into the thermos cup to be cleaned, then press the broken eggshell with a rag to scrub the cup, and then rinse it with clear water. The thermos cup can also be cleaned.